On Tuesday afternoon, the Republican 52-seat Senate majority grew more vulnerable with an announcement from outspoken Trump critic Jeff Flake (R-AZ), who says he will not seek election in 2018. He made his announcement on the Senate floor (via the above CNN video), from where he stated, “We must never meekly accept … the personal attacks, threats against principles, freedoms, and institutions, the flagrant disregard for truth and decency, the most reckless provocations, often for the pettiest reasons.”

Flake further laments these “appalling features of our current politics,” and given his antagonistic history with President Trump, one could only assume that he’s taking a direct shot at the commander-in-chief. Indeed, he further stated, “If I have been critical, it not because I relish criticizing the behavior of the President of the United States.” He then took on Trump’s tweets:

“The notion that one should stay silent as the norms and values that keep America strong are undermined and as the alliances and agreements that ensure the stability of the entire world are routinely threatened by the level of thought that goes into 140 characters — the notion that one should say and do nothing in the face of such mercurial behavior is ahistoric and, I believe, profoundly misguided.”

While Flake hasn’t been doing great in the polls, Trump hasn’t helped the senator’s situation. In August, the president tweeted about “Flake Jeff Flake,” who Trump also called “toxic” as well as “WEAK on borders, crime and a non-factor in Senate.” That tweet arrived after Flake penned a scorched-earth op-ed that accused his party of selling its soul to Trump.

In light of Flake’s announcement, John McCain thanked his fellow Arizona senator for his “honorable service” to the state and the U.S.

Thank you to my dear friend @JeffFlake for your honorable service to the state of #Arizona & the nation.

In announcing his impending retirement, Flake joins the outgoing likes of another vocal Trump critic (clearly, there’s a theme here), Bob Corker (R-TN), who has entered into a massive and lengthy feud with the president. One can expect the fights to continue. 2018 may be even wilder than 2016, folks.

In the below video, McCain took the Senate floor to praise Flake as a “man of integrity and honor” who “stands up what he believes in.”

And Senate Majority Leader Mitch McConnell addressed Flake as “a team player,” but he did not address the subject matter of Flake’s announcement.